Refrigeration & Air Conditioning USCG Question #978 (Set 19)

As shown in the illustrated LP centrifugal chiller pressure maintenance system, what is its functional purpose? Illustration GS-RA-40 Illustration GS-RA-40: the U.S. Coast Guard has not released this illustration.

Official USCG Answer & Rule Citation

Correct Answer: Option D — prevent the entrance of air into the chiller when the chiller is idle

Low-pressure (LP) centrifugal chillers operate below atmospheric pressure. The pressure maintenance system introduces a slight positive pressure or heat blanket when idle, preventing ambient air and moisture from infiltrating the chiller casing during shutdown periods.

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